Huge pipelines are used to transport liquid materials of varying kind over many miles. Often it is desirable to extend the pipeline across the floor of large bodies of water, e.g. lakes and ocean bays. Typically the pipe sections are fabricated in lengths as long as feasible for handling. The lengths are then positioned in sequence along the selected route and joined together, each new section being positioned and joined to the end of the pipeline of previously interconnected sections.
The procedure for assembling the pipe sections underwater, as when spanning a lake or ocean floor, presents special problems. The assembling process previously employed requires manual handling of certain aspects of the process. Assemblers in an underwater situation are required to perform the work in diving suits or through manipulators on specially-designed submarines. Such underwater manual participation is difficult, time-consuming, dangerous, and very costly.
Pipeline sections as contemplated for the present invention are huge, in the range of 3 to 10 feet in diameter, up to 1000 feet in length and weighing many thousands of pounds. The sections are typically transported on large barges or by fastening floats to the pipe and towing them to the job site. At the job site, large cranes carried by barges or ships are employed to unload or detach the pipe sections from the barge or floats and lower them into the water. Manual participation up to this point involves attaching some kind of harness to the pipe for hook up to the crane, manipulation of the crane, and visual observation and direction of the handling process by supervisors, all accomplished by personnel from above the water's surface.
Once the pipe section is lowered into the water, the tasks involve various forms of; positioning the pipe section (properly oriented end-to-end) adjacent the pipe section previously laid; bringing an end flange of the new pipe section into abutment with an end flange of the prior pipe section so that bolt holes through the two flanges are aligned; inserting bolts through the aligned bolts holes and threading nuts onto the bolt ends; and releasing the harness from the pipe which is then brought to the water's surface for attachment to and laying of the next pipe section.